The mobility rEVolution: Second-life battery applications with ‘pick-n-mix’ cells connected in series

Connecting and operating very different cells as desired in second-life applications referred to as patchwork batteries could soon become a viable option thanks to a novel technology developed by Germany-based Benning CMS Technology. By virtue of its patented algorithm embedded in the charging process called ETA-Leveling, battery cells from different manufacturers, of different ages and at different nominal capacity can be connected and operated in a series. During charging, the algorithm treats each cell as if it were part of a single-cell battery application, thanks to efficiency leveling. Through targeted correction of the conversion efficiency, all cells connected in series are levelled so that they all have a uniform overall efficiency and thus achieve the end-of-charge voltage at the same time. “Up until recently, we ourselves would’ve never thought that combining cells randomly would work. It has not been possible with any of the traditional BMS [battery management systems],” says Frederik Fuchs, managing director of Benning CMS Technology. “Manufacturer, age, nominal capacity, cell chemistry – it really doesn’t matter. Our leveling process also recognizes which cells are a reasonably sensible match based on their capacities. We then combine these cells to a long-lasting battery block that works perfectly.” The company confirms for pv magazine that patchwork batteries with different cell chemistries have been limited to the demonstration phase, whereas in all other cases the systems work seamlessly with same chemistry cells from different manufacturers, of different ages and at different nominal capacity. As such, the technology could potentially unlock massive opportunities for reusing discarded battery modules that tend to end up on landfills due to prematurely aged cells. Whereas these weakest cells determine the capacity of the entire block, most of the cells in the discarded block are still in excellent condition or at least too good to recycle them. According to the company, ETA-Leveling can also be used as a BMS in the first place to prevent the premature ageing of cells as well as in defective blocks, where it can best re-level the cells so that the block can continue to be used. Already available for licensing, ETA-Leveling is suitable for battery blocks of all kinds – including all EV and stationary storage applications — and it requires no hardware changes.

Some 50 kilometers from the Acrtic Circle in Sweden, British luxury automaker Rolls-Royce Motor Cars has got a step closer to launching its first all-electric vehicle, Spectre, after completing winter testing in temperatures as low as -40℃. The carmaker has shared that the Spectre has now covered 25% of the planned 2.5 million test kilometers, simulating 400 years of use on the new EV. Its first all-electric vehicle will be by far the most technologically advanced and connected Rolls-Royce ever, and will align with the prophecy of an all-electric future of one the company's founders, Charles Rolls. “The electric car is perfectly noiseless and clean. There is no smell or vibration. They should become very useful when fixed charging stations can be arranged,” Rolls said back in 1900.